Resistance-capacitance combination substitution instrument



Se t. 27, 1960 R. s. DUGOT 2,954,518

RESISTANCE-CAPACITANCE COMBINATION SUBSTITUTION INSTRUMENT Filed Aug.11, 1958 2 Sheets-Sheet 1 Sept. 27, 1960 R. s. DUGOT 2,954,518

RESISTANCE-CAPACITANCE COMBINATION SUBSTITUTION INSTRUMENT Filed Aug.11, 1958 2 Sheets-Sheet 2 INVENTOR. J 08 B 29 W d'ffow/weyi 2,954,518Patented Sept. 27, 1960 RESISTAN CE-CAPACITAN CE COMBINATIONSUBSTITUTION INSTRUMENT Richard S. Dugot, Jackson Heights, N.Y.,assignor t Electronic Instrument Co., Inc., Long Island City, N.Y., acorporation of New York Filed Aug. 11, '1958, Ser. No. 754,283

11 Claims. (Cl. 323-74) This invention relates generally to apparatus ofthe broadly classified category, electronic instruments, and moreparticularly is concerned with a novel arrangement of resistance andcapacitance elements with switching means suitably connected therewith,and the whole being assembled ina portable housing for use as aso-called substitution box.

There are many substitution boxes on the market, in which there is anarrangement of different values of resistors or condensers connected sothat the user may connect the box into a circuit where it is desired toascertain the effect of substituting different values. Such instrumentsare valuable in servicing television and radio receivers, in laboratoryand experimental work, and comprise an aid in engineering circuitry ofdiiferent kinds. Primarily, the availability of a large number ofcapacitors or resistors saves considerable time in computing such valuesas required for diiferent purposes, and in addition enables computedvalues to be assayed or varied as to their values in circuitry. I

The primary object of the invention is to provide a novel substitutioninstrument in which a large number of different combinations ofresistance and capacitance, both in series and in parallel may beachieved through the use of an extremely simple circuit and switchingmeans associated therewith.

A further object of the invention is the provision of a novelsubstitution instrument of the character described in which a singleselector switch eifects the connection of the chosen elements in a.variety of diiferent arrangements for different positions of the switch.

Other objects of the invention are concerned with the construction ofthe instrument which has extreme versatility but which is simple inoperation and compact so that it is readily portable and hence highlyuseful for servicemen.

Many other objects will occur to those skilled in the art to which thisinvention appertains, as a detailed descrip tion of a preferredembodiment is set forth hereinafter, in connection with which thedetailsof construction have been illustrated in suitable drawings.

In said drawings:

Fig. 1 is a perspective view of an instrument constructed in accordancewith the invention, to show the housing, the selector switches and theterminals thereof;

Fig. 2 is a circuit diagram of the instrument which is illustrated inFig. 1, the circuit selector switch being shown in Open position;

' Figs. 3, 4, 5, 6 and 7 are diagrammatic views showing the connectionsprovided by the circuit selector switch when it is in the followingconsecutive positions: Series R.C., Capacitors, Resistors, Parallel R.C.and Short.

Fig. 8 is a circuit diagram of a basic integration network which can beachieved with varying values of the elements thereof by means of theinvention; and

Fig. 9 is a circuit diagram of a basic differentiating network which canbe achieved with varying values of the elements thereof by means of theinvention.

The invention generally comprises a circuit which has means forconnecting capacitors and resistors thereinto, and which has acircuit-selecting switch which eifects the connection of the componentsinto various combinations so that the user can achieve diiferent effectsby connecting the terminals of the instrument into a circuit upon whichhe is operating.

As illustrated in Fig. 1, there are only five controls on theinstrument, designated generally by the reference character 15, andthese five are all mounted on the face of the panel 17 which is mountedto a suitable housing 19, preferably of insulating material. There arefour rotary selector switches 21, 22, 23 and 24 and a slide switch 25.The functions of these switches will be disclosed as the descriptionproceeds. The panel 17 also has mounted thereon two or three terminalsor binding posts, three being provided in the embodiment describedherein and being designated 27, 29 and 31.

The rotary switch 21 is the circuit selector switch, the

rotary switch 22 is the capacitor selector switch, the rotary switch 23is a low range resistor selector switch, and the rotary switch 24 is ahigh range resistor selector switch. The slide switch 25 has only twopositions and it connects either the high or low resistor group into theoperating circuit.

As noted from Fig. 1, each of the switches 22, 23 and 24 have a greatmany positions, compared with the switch 21 which has but six. Thenumber of positions of the rotary switches 22, 23 and 24 depends uponthe ranges of values desired to be covered, the value of the stepsdesired between consecutive values, the economy desired, and otherfactors. The instrument illustrated was constructed to sell in themedium price range and each of the rotary switches 22, 23 and 24 hadeighteen positions providing eighteen different values of capacitanceand 36 different values of resistance.

The exact values and ranges used will depend upon the uses to which theinstrument 15 is intended to be put, but in the commercial version ofthe instrument described herein, which was intended especially forgeneral television, radio and audio servicing, the ranges were asfollows:

Capacitors: .0001 to .22 microfarad with about 25% to 50% increasebetween values.

Resistors: One range from 15 to 10,000 ohms with about 25% to 50%increase between values; a second range from 15.000 ohms to 10 megohmswith about the same increase between steps as the first range.

In Fig. 2 the internal circuit of the instrument 15 is illustrated. Thecapacitors are designated C-l, C-2, C3, etc., to C-18; the resistors ofthe low range are designated R-l, R2, R3, etc., to R-IS; and theresistors of the high range are designated R-19, R-20, R-21, etc., toR-36. The components are shown arranged radially, and as a practicalmatter they may be physically mounted and connected in this manner. Theouter electrodes of the capacitors C-1, C-2, C-3, etc., are allconnected to a common circular conductor or bus 30 which connects by thelead 32 with a common junction terminal 34 and extends thence by way ofthe lead 36 to the wiper contact 38 of the rotary switch 21. The innerelectrodes of the condensers are connected respectively to contactterminals T-l, T-2, T-3, etc., to T18, which are arranged circularly tobe engaged by the wiper 40 of the rotary switch 22. The wiper 40 issuitably mounted in conjunction with detent means so that the contactterminals T1, T-2, etc., to T18 are engaged consecutively in steps, andthis is also true of all of the contact terminals of the switches 23, 24and 21.

The wiper 40 connects by the lead 42 to the wiper contact 44 of therotary switch 21.

The switches 23 and 24 both have circular conductors or bus rings 46 and48 respectively which are similar to the bus ring 30 and which also areused in the physical embodiment to support the resistors connectedtherewith. Bus rings 46 and 48 are connected as at 50, the opposite endof the ring 46 being connected by the lead 52 to the wiper contact 54 ofthe rotary switch 21. The opposite end of the ring 48 is free.

The resistors R-l, R2, etc., to R-dS are arrange radially as shown, andeach has one terminal connected to the ring 46 and the opposite terminalconnected to a contact terminal T19, T2, etc., to T36 respectively, thecontact terminals adapted to be wiped by the wiper 56. The wiper 56connects by lead 58 to one contact 60 of the switch 25, the othercontact 61 being connected by the lead 63 to the wiper 64 of the rotaryswitch 24. The resistors R-l9, R-20, etc., to R-36 are connected andmounted on the ring 48 similarly to the manner in which the resistors ofthe switch 23 are mounted and connected. The inner contact terminals areT-37, T-38, etc., to T-54.

The arm 66 of the switch 25 is connected to the common junction terminal34. The switch 25 therefore connects one or the other of the groups ofresistors of the switches 23 and 24 to the wiper contact 38. The wipercontact 68 connects by the lead 76) to the terminal or binding post 27,and the wiper contact 72 connects by the lead 74 with the binding post29.

The switch 21 has six positions, as described above, and is called thecircuit selector switch because its position will determine theconnections which are established between the groupings of componentsand the binding posts 27 and 29. The switch 21. has two arcuate contactmembers 7 6 and 78 which are insulated from one another and mounted upona rotatable wafer such as indicated schematically at 80. Rotation of thewafer 80 will change the positions of the arcuate contact members 76 and78 circumferentially, not with respect to one another, but with respectto the fixed wiped contacts 44, 38, 72, 54 and 68 which are radiallyarranged about the wafer.

In Fig. 2, the rotary circuit selector switch 21 is in a positionwherein the circuit of the instrument is open, and hence this isdesignated Open position. It will be noted that the radially outwardlyextending car 82 is the only portion of either of the arcuate contactmembers 76 and 78 which engages any wiper contact, the wiper contact 68in this case being the one which makes electrical contact with thearcuate member 78. Note that the wiper contact 72 is clear of either ofthe arcuate contact members and hence the terminals or binding posts 27and 29 look into an open circuit. This condition is useful in circuitWork since it defines infinite impedance. It is easily achieved in theinstrument 15 by merely turning the switch 21 to said Open position,regardless of the positions of any of the other switches.

In Fig. 3 the switch 21 has been turned to its next circumferentialposition which is designated Series RC. The wiper contact 54 nowelectrically contacts the ear 82 and the wiper contact 72 also engagesthe arcuate member 78 so that the terminal or binding post 2'9 isconnected by the lead 52 to the rings 46 and 58 in series. The wipercontact 4 is now in electrical engagement with the large segment orextension 84 of the arcuate contact member 76 which also engages thewiper 63. Since 68 connects with the terminal or binding post 27, andthe wiper contact 44 connects with the capacitor grouping, an electricalpath is established from the binding post 27 to the wiper 46. Thecircuit bet een the binding posts 27 and 29 is completed by virtue ofthe junction terminal 34, from the rings 46 and 48 through a resistor inone or the other groupings, depending upon the position of the switcharm 66. As illustrated specifically, if; the switch positions ofswitches 22, 23,24 and25 were as inFig. 2,

and the position of the switch 21 as in Fig. 3, the binding posts 27 and29 would be connected to a circuit which included C-18 and R-19 inseries.

In the event that the user wishes to change the values of the resultingseries circuit, this can be done without disconnecting the test circuitfrom the binding posts. All that the operator need do is change thepositions of the switches 22 and 24. This is done in the well-knownmanner of merely manually rotating a knob such as shown in Fig. 1. Ifthe low resistor range is desired instead of the high, the operatormerely slides the slider of the switch 25 to its. opposite position.Furthermore, the user has infinite impedance condition available byrotation of the switch 21, and the other positions which will bedescribed hereinafter give other conditions which may be needed at amere twist of the knob of switch 21.

In Fig. 4 the switch 21 has been rotated to its next circumferentialposition from that of Fig. 3, said position being designated Capacitors.In this position, note that the wiper contacts 38 and 72 both engage thearcuate contact member 7 8 and hence the junction terminal 34 isconnected to the binding post 29. The wiper contact 54 is between thearcuate contact members 76 and 78 and hence, since this provides theonly electrical path to one side of the resistor groups, there are noresistors connected into the resulting circuit. The wiper contacts 44and 68 are both in electrical engagement with the extension 84 therebyestablishing electrical continuity between the binding post 27 and thewiper 40 of the switch 22. Since the ring 30 also connects with thejunction terminal 34, it will be seen that in this position of theswitch 21, only capacitors are connected in the circuit. Any value ofavailable capacitance can be chosen, even after the instrument 15 isconnected into the test circuit, by merely changing the position of thewiper 40 through manipulation of the knob 22.

In Fig. 5, the switch 21 has been changed to its next position byrotation of the knob which, of course, carries the wafer with it, as inall switch movements. In this condition, the two wiper contacts 38 and72 are still connected together, but now the wiper contact 44 is nolonger in the circuit, and in its stead the contact wiper 54 isconnected with the contact wiper 68 and hence to binding post 27. Sincethe wiper 54 connects to the resistor groupings, it will be obvious thatthis position of the switch 21 provides a circuit in which there is onlya path to the resistor groupings, and in the manner which has beendescribed, any one of the thirty-six resistors can be chosen andinserted into the circuit. This position is designated Resistors.

The next position, designated ParallelRC. is achieved by rotating theswitch wafer 80 to the next circumferential position. This is shown inFig. 6. In this position, wipers 38 and 72 are still connected togetherwhich establishes a path from the binding post 29 to the junctionterminal 34. Now, all three of the wiper contacts 44, 68 and 54 areengaged with the arcuate contact member 76. The ear 86 provides for thecontact with the wiper 44. The binding post 27 is now connected to boththe capacitor grouping and the resistor groupings because the wipercontact 44 extends to the wiper 40 of the switch 22 and the wipercontact 54 connects with the rings 46 and 48. The particular capacitorand resistor which are in the circuit are now in parallel with oneanother and together connected between the binding posts 27 and 29.

The next position of the switch 21 is illustrated in Fig. 7, and it willbe obvious that this position, designated Short is a short circuitbetween the binding posts 27 and 29 by way of the wiper contacts 68 and72 through the arcuate contact member. This is a useful condition incircuit work also.

As thus far described the instrument 15 provides a highly efiicientsubstitution box in which the user has at his finger tips resistancealone, capacitance alone, resist ance and capacitance in series, andresistance and capacitance in parallel. Furthermore, the values of theresistance and capacitance may be quickly changed without disconnectingthe instrument from the circuit, or short circuit orinfinite impedanceconditions can be achieved by a twist of the knob of the circuitselector switch 21. The versatility and flexibility of the instrument isreadily understood from the above description, and such versatility andutility is multiplied when using more than one instrument. The low costpossible because of the simplicity of the instrument enables the user topurchase more than one without hardship.

The instrument can be rendered additionally useful and versatile by thesimple connection of a conductor 90 from the junction terminal 34 to thethird binding post 31, previously described herein, but not discussed.

This connection, it will be seen, provides an externally availableterminal between the capacitor and resistor groups in addition to theterminals defined by the binding posts 27 and 29 for the variouspositions of the switch 21. The only position of the switch 21 which isaffected by the addition of this connection is the Series R.C. position,which connects a resistor and condenser in series. The additionalconnection therefore provides, at the binding post 31, an electricalpath which leads to the junction between the condenser and the resistor.

Thus, the user may connect the resistor and condenser into twocompletely different parts of a circuit, providing that there is acommon point for one side of each of the components. Such circuitry isnot unusual, since it occurs in many circuits, the common point usuallybeing ground. Likewise, the individual effect of the respectivecomponents may be ascertained while the pair are connected into acircuit, since the junction between them is available.

A particularly interesting use of the junction between the resistor andcapacitor of a series arrangement is in pulse shaping, forming andcomputing. The basic passive networks of many circuits are integratingcircuits, diiferentiating circuits, and variations thereof. Suchcircuits also use T and pi sections, the latter also found in filternetworks, and delay lines. In Fig. 8 there is illustrated a simpleintegrating circuit made up of a series capacitor C and a shuntingresistor R. The input is across the binding posts 27 and 29 and theoutput is across the binding posts 29 and 31. These are the bindingposts of the instrument 15. In Fig. 9 there is illustrated a simplediiferentiating circuit made up of a series resistor R and a shuntingcapacitor C. The input is across the binding posts 27 and 29 again, butin this case the output is across the binding posts 31 and 27.

The two simple networks of Figs. 8 and 9 are formed with the instrument15 without in any way changing the construction or connections of theinstrument, except for the additional conductor 90 and the binding post31. The numbers of the resistor R and the capacitor C are omitted, sincethese merely represent the capacitors C-l, C-2 etc., to C-18 and theresistors R-l, R-2 etc., to R-36.

Through the use of two or more instruments 15 modified with the additionof the connection between R and C an extremely valuable tool for circuitwork can be formed since T and pi sections are readily formed forinsertion into test circuits. The ease with which the values of thecomponents can be varied enables considerable computation time to besaved.

Many additional uses and applications of the invention are easily withinits capabilities. Obviously, variations in the details and specificarrangements of the parts are possible without in any way departing fromthe spirit or scope of the invention as defined in the appended claims.

What is desired to claim by Letters Patent of the United States is:

I claim:

1. An electrical component substitution instrument comprising, a firstgrouping of components of a first type and means for selecting a desiredone of said components 6 for connection into an external test circuit, asecond grouping of components of a second type and means for selecting adesired one of said latter components for connection into an externaltest circuit, a pair of terminals adapted for connection to saidexternal test circuit, a single circuit selector switch, a commonelectrical junction between the groupings, a plurality of contactsconnected respectively to said groupings, said terminals, and saidcommon junction, and said switch having contactengaging means forelectrical engagement with said contacts, said means movable to any oneof a plurality of different pre-selectable positions in which said onegrouping is connected across said terminals, said second grouping isconnected across said terminals, the groupings are both connected inparallel across said terminals, or the groupings are connected in seriesacross said terminals.

2. An instrument as claimed in claim 1 in which there is a thirdterminal and said third terminal is connected with said common junction.

3. An instrument as claimed in claim 1 in which one of said groupings isformed of two sub-groupings and said selecting means of said onegrouping includes means for selecting between sub-groupings.

4. An instrument as claimed in claim 1 in which said circuit selectorswitch includes a pair of arcuate contact members insulated from eachother and mounted on a rotatable wafer, said contact engaging meanscomprising a plurality of ears projecting from the outer circumferenceof said contact members.

5. An electrical component substitution instrument comprising, a firstsub-circuit having a plurality of electrical components adapted to beconnected therein and first switch means for connecting any one of saidcomponents in said sub-circuit, a second sub-circuit having a pluralityof electrical components adapted to be connected therein and secondswitchmeans for connecting any one of said last-mentioned components insaid subcircuit, a pair of output terminals, a single switch means forestablishing a plurality of different conditions of circuit connectionof said components across said output terminals, including one conditionin which the selected component of the first sub-circuit and theselected component of the second sub-circuit are in parallel across saidoutput terminals and a second condition in which said selectedcomponents are in series across said terminals.

6. An instrument according to claim 5 in which there are two additionalconditions, in which the respective selected components are individuallyacross said terminals.

7. An instrument according to claim 5 in which there is a third terminaland a common connection between said sub-circuits, and the thirdterminal being connected to the common connection.

8. An electrical component substitution instrument comprising, a firstgrouping of capacitors and a switch for selecting a desired one of saidcapacitors for connection into an external test circuit, a secondgrouping of resistors and a switch for selecting a desired one of saidresistors for connection into an external test circuit, a single circuitselector switch including a pair of arcuate contact members insulatedfrom each other and mounted on a rotatable water, a common electricaljunction between the groupings, a pair of terminals adapted forconnection to said externaltest circuit, a plurality of contactsconnected respectively to said groupings, said common junction, and saidterminals, and a plurality of contact engaging ears projecting from theouter circumference of said arcuate contact members, said earselectrically engageable with said contacts and movable to any one of sixdifferent pre-selectable positions whereby an infinite impedance isprovided across said terminals, said first grouping is connected acrosssaid terminals, said second grouping is connected across said terminals,the groupings are both connected in parallel across said terminals, thegroupings are connected in series across said terminals, or a shortcircuit is provided across said terminals.

9. An instrument as claimed in claim 8 in which said second grouping isformed of two sub-groupings of resistors and includes a second switchfor selecting between said sub-groupings.

10. An instrument as claimed in claim 9 in which the capacitors andresistors in each of said groupings are circularly arranged andconnected by a circular bus which is coaxial with its respectiveselecting switch.

11. An instrument as claimed in claim 10 in which there is a thirdterminal, said third terminal being con- 1,429,227 Dubiler Sept. 19,1922 1,491,341 Eaves Apr. 22, 1924 2,857,528 Bertin Oct, 21, 1958FOREIGN PATENTS 362,511 Great Britain Dec. 7, 1931

